How to have something not be counted as a bors command

You don’t have to treat it as “that which must not be named”. Just don’t have bors at the beginning of the line. You can do that by prefixing the line with a single space, just like you do if you want a URL in Discourse to not get counted as a onebox:

bors try
There's a space in front of the word "bors".

Bors also won’t respond if there’s other Markdown formatting between the start-of-line and the keyword. For example, it won’t be triggered by a block quote or the inside of a table if the leading or trailing pipes are used:

This will not trigger a command:
> bors try
| name | description |
|----------|----------------------------------------|
| bors try | This will not trigger a command either |

Bors will, however, match it’s keyword case-insensitively. So this will count as a bors command: